Fluoroalkylphosphoric compounds



l afentecl May 20,1952

UNI-TED vs TAT-Es 'Nolhawing. Application June 29 1950, Serial No. 171,246

*3 Claims. (Cl. 260-461.)

This invention relatesft-o 'anewlclass of fluorinated organic compounds and, more particularly, to certain fluoroalkylphosphoric esters and salts thereof.

Little is known of the fiuoroalkylphosphoric esters. In particular, there is no description in the chemical literature of the fiuoroalkylphospho'ric esters having a. multiplicity "of 'difiuoromethylene, -CFz-, groups.

An object ofithe present invention isto provide anew class of fiuorinated organic compounds of technological interest. -l-A further object is to provide :.a class of fluoroalkylphosphoric esters and salts thereof characterizedby their stability and-value in various technological uses. A more particular object isito provide such a class of compounds which are excellent dispersing agents. Other objects will be apparentirom the description o'f the invention given hereinafter.

:The above objects are-accomplished according to thezpresent invention by providing a class of fluoroalkylphosphoric compounds having the formula (H-(CFz) inCH OD-mPOiOMly wherein n is an integer from 1 to'5, inclusive, a: is an integer from 1"to3,'inclusive, 4/ equals 3-:0, and M ishydrogen, alkali metal; ammonium, or substituted ammonium. Because of their uniquevalue as dispersing agents the preferred compounds are i the "water soluble compounds having the above formula wherein :cis 1. or 2 and, still more preferred, are those compounds where M is the ammonium radifcal.

The starting materials for the preparation of the fluoroalkylphosphoric compounds of this invention are the corresponding iluoroalkanols of the. formula H(CF2)211CH2OH which can be .prepared by polymerizing ftetrafluoroethylene in the presence of methanol' and of a ,peroxy "or are catalyst ati50 C. to 350 'C. as described in U." S.

application Serial 'No.65,063 filed in the name of R.M..Joyce on December 13, 19418, new Patent Nc: 12;559;628, dated July 10; 1951. Thi'sreaction produces a mhtture of the alcohols .HlCFzleaCHaOH wheren varies from 1 -to 12 or more. "This mixture can 'beused as obtained or it can be separated prior to conversion of the fiuoroalkanols into the phosphate esters. The desired fluoroalkanolscan be separated by conventional methods suchas fractional distillation, crystallization vention' are the members where "n is an integer .12 r from 1 to '5, inclusive, in-the aboveiormulja and which can be ,p'repared conveniently essentially according to Example 1Vv of said application Serial No. 65,063, usingiditertiarybutylperoxide as the catalyst.

The fluo'roalkylphosphoric cdmpoundsor this invention fall .into the following three types:

H('CF 2) zhCHzOPO (OM): =(-I-I( CF2J21ZCH2O)2PO(OM) (Hi CF23 alGHzO 9' 3P0 n, being an integer from 1 'to 5, inclusive, andM being 'l;ydrogen,.alkali metal, ammonium, or substituted ammonium.

A general synthesis ior all these compounds is reaction. of the appropriate fiuoroall anol with phosphorus 'o'iiychloride, P0013. This reaction is ordinarily carried out in the .presence of pyridine as an 'HClaccep'tor. .The monoalkyl phosphates can also be jprepared j by treating phosphorus pentoxide, P205, withtwoinols of the appropriate fiuoroalkanbhiollowed.by hydrolysis of the "resulting. pyrophosphate. Thelpr'odu c't 'can'then be isolated as'suchor, precipitated astheammonium I salt by the addition of ammonia to the. reaction mixture. Alternatively a solution of salts of the mixed mono-t and lfdi- .esters can be prepared by neutralizin'g'a mixture of the. acids with aqueous ammonia-Ian .amine or alkali metal hydroxide.

Likewise, .the dialkyl phosphates can be prepared byreactibh of two m'ols ofJth'efiuor'oaL kanol with one mol of phosphorus pentoiiide. .Instead-of hydrolysis, however, the intermediate .pyrophos'phateis heated toI200-.-300 .C.;at extreme- 1y lowpressure. For the. lower membersbrthe series a pressure of 1-2 mm. is satisfactory but the higher ones require a considerably higher vacuum. For .example, the ..pressure for the preparation of the eleven carbon atom member by'this method-must be about*0;01 mm. 'In any case,; the ,foverhea-d' product consists of a mixture:containing predominantlyj dialkyl acid phosphatesw-ith some regenerated alcoholand trialkyl phosphates.

An alternative method for preparing and sepa ratingafmixture ofthe monoand dialkyl esters from the trialkyl "derivatives is "as follows: the appropriate iiuoroalkanol "(2+4 mols) is treated with one mol of phosphorus '-pentoxide at 80fC'.- 180C. The {resulting iniXedracid phosphate is neutralized with aqueous "ammonia, an amine, tetraalkylammonium base, or alkali metal hydroxide to give a solution, or is dissolved 'in'toluene andg'gassed with ammonia to precipitate a mixture of the salts of the'corresponding monoand solids. The di-Cs (three carbon atom) acid phos- 2 phate is liquid whereas the di-Cu acid phosphate is a soapy white solid. Similarly, the trialkyl C3 and C5 compounds are liquid while the tri-Cn is a white powder. These properties are summarized as follows:

Melting Range Boiling Point Monoalkyl acid 65.068.0 G.

C Di alkyl acid..- below room tem Di alkylN l57158 G Tri alkyl 63-6 1 C./0.04 mm. Di alkyl acid 200 C./5 mm.

Di alkyl N11 Tri alkyl C Mono alkyl acid.

C11..- Di alkyl NH4... Tri alkyl The crude mixed acid phosphates vary in color from pink to dark brown. Their physical state varies from thick liquids for the lower members to brittle solids for the higher. The ammonium salts vary from white powders to soaps depending on the relative proportions of monoand di-esters. The consistency of these various mixtures is not readily predictable apparently because several of the mixtures form low melting eutectics.

The compounds of this invention have been identified by analysis for phosphorus and/or nitrogen contents. A superior method for identification of the acid phosphates is potentiometric titration. The single atom of hydrogen of the dialkyl phosphates and the first hydrogen of the monoalkyl phosphates titrate in ethanol to give a plateau at pH 2-4. The second hydrogen of the monoalkyl phosphates shows a plateau at pH 8-10. From the relative lengths of these plateaus it is possible to identify the compounds and to determine their purity. Although titration of phosphoric acid itself produces the same two plateaus, this acid is easily detected by its low equivalent weight.

The following examples wherein all parts are by weight unless otherwise stated, illustrate the preparation of representative specific compounds of the present invention.

EXAMPLE I.C3 ESTERS Mono alkyl ester.To 132 parts of tetrafluoropropanol, H(CF2)2CH2OH (B. P. 74 C./200 mm.) there was added slowly 71 parts of phosphorus pentoxide with agitation at room temperature. The temperature was raised to 50 C. and parts of water added. The resulting hydrolysis raised the temperature further to 90 C. Titration of the reaction mixture with 0.1 N NaOI-I showed that it contained 79% of monoalkyl phosphate and 2 1% of dialkyl phosphate.

The mono ester was isolated in the form of needle-like crystals by heating 50 parts of the above material in 1300 parts of toluene and allowing to stand for several hours. This crystalline material was found by titration in ethanol to have a neutral equivalent of 104. The theoretical propanol.

4 value for mono(tetrafiuoropropyl) phosphate is 106.

Dialkyl ester.0ne hundred and thirty-two parts (1.0 mole) of tetrafluoropropanol was cooled to 0 C. With rapid agitation 71 parts of phosphorus pentoxide was added and the temperature rose to 112 C. The temperature was then raised to 160 C., held for 40 minutes, and then dropped to room temperature. The mixture was distilled, giving 157 parts of product in the form of a light gray-straw colored material boiling up to about 210 C./ 0.2 mm. Titration showed this to contain 127 parts of di(tetrafiuoropropyl) phosphate, equivalent to a 78% yield based on the tetrafluoro- This was converted to the ammonium salt by dissolving in toluene and treating with NH3. The ammonium cli(tetrafluoropropy1) phosphate was filtered, washed with petroleum ether and dried.

Analysis: Calculated for (H(CF2) 2CH20) 2P0 (ONT-I4) Calculated Found Percent P The ammonium salt underwent a transition from solid to liquid at 156.9 C.-158.2 C.

Trialkyl ester.-Sixty-six parts (0.49 mol) of tetrafiuoropropanol, H(CF2)2CH2OI-I, was charged into a reaction vessel with parts of pyridine and 45 parts of dry benzene. At a rate designed to hold the temperature of the reaction mixture at 10 C., 26 parts of phosphorous oxychloride (0.17 mol) was added. The reaction mixture was refluxed for 2 hours after the addition of the phosphorus oxychloride, and pyridine hydrochloride precipitated. After the reaction mixture had cooled to room temperature. 85 parts of water was added. The benzene layer was separated, washed with water, and then dried and completely neutralized by treatment with solid sodium carbonate. After the removal of the benzene, the crude product was distilled at 0.04 mm., giving 31 parts boiling at 63 C.- 64 C. The tri(tetrafluoropropanol) phosphate was a thin, light green liquid containing 7.12% P (theory 7.06%).

EXANIPLE lI.-C5 ESTERS Diallcyl ester.Sixty-seven parts of phosphrous pentoxide (0.471 mol) was rapidly added to 200 parts of octafiuoroamyl alcohol,

(0.863 mol), vigorously stirred, and cooled to approximately 5 C. After a period of 10-20 seconds, an exothermic reaction occurred which carried the temperature up to C.- C. The cooling bath was then Withdrawn and replaced by a heater and the reaction mixture was heated up to C. over a period of 0.5 hour. This reaction mixture was then distilled over a range of 30 (I-260 C./2-4 mm. The product of 194 parts of reddish-brown viscous liquid was a mixture of the 'octafiuoroamyl alcohol and the various alkyl phosphates. It was dissolved in 860 parts of boiling toluene and gaseous ammonia bubbled in to give 154 parts (65% conversion) of ammonium di(octafluoroamyl)phosphate as a crystalline, white solid.

This same ester was also prepared from phosphorus oxychloride as follows: Into a refluxing mixture of 38 parts (0.25 mol) of phosphorus solved in.ether.and dried over Drierite.

tillation the major fraction, '73 parts of triwoi ychloride :and :0.5.;part ;of pyridine itherewwas added :dropwise. 1116 parts 0.50.;mo1) of :octafluoroamylalcohol. .;Aiter the evolution of h .droeen :chloride had ceased, the product was first crudely idistilled and then fractionated .to give g -twor major :;fractions, the trialkylphosphate boiling: at .1611:/7 :mm. and the dialkylphosphate bo l'i-ngpat 200/5mm. The .dialkylphosphate wasdissolved;i;n;250:-parts ofzboiling toluene and 'ltherammoniumxsalt precipitated .in; white, feath- -.ery;=crystals through the. addition of dry,:gas.eous

ammonia. The ammonium salt. melted sharply 1at 1;90 C- Analysis calculated for 11?, 25.72311, 2.53; neutralization equivalent,-5,43.

.Found: 1?, 5.33; N; 262; neutralization equiv- .alent, 558.

(octafiuoroamy) phosphate (23.6% conversion) was obtained at 161/7 mm. It was a clear, colorless, odorless, slightly viscous liquid with a specific gravity of approximately 1.6.

EXAMPLE III.-C7 ESTERS Ammonium dodecafluoroheptyl phosphate- One-tenth mol (33.2 parts) of dodecafluoroheptanol, I-I(CF2)sCH2O'H, B. P. 170-171 0., was mixed at room temperature with 0.05 mol (7.1 parts) of; phosphorus pentoxide. The mixture warmed up slightly upon mixing and it was heatedwith stirring at about 50 C. for '30 minutes when it became slightly brownish. About '50 parts of distilled water was then added to hydrolyze .the fiuoroalkyl phosphoanhydrides and unreacted phosphorus pentoxide. The mixture was dissolved in dioxane and boiled for several minutes. Treatment with gaseous ammonia precipitated the ammonium fluoroalkyl phosphate. This material was dissolved in absolute ethanol and the insoluble ammonium phosphate was filtered off. The monoammonium dodecafiuoroheptyl phosphate was precipitated from the ethanol solution by boiling off the ethanol with toluene. The yield was 60.5%.

Analysis calculated for H(CF2) sCHzOPO (OH) (ONI-Ii) P, 7.21; N, 3.26. Found: P, 7.41; N, 3.32.

Mono(dodecafluoroheptyl)phosphate. Onehalf mol of dodecafluoroheptanol was mixed with 0.25 mol (36 parts) of phosphorus pentoxide in a stirred container. The temperature was kept at about 80 C. for 1 hour. The reaction is exothermic and the temperature was maintained at 80 C. for -30 minutes without external heating. After the addition of parts of water the mixture was heated at 80 C. for 15 minutes. The slightly pink crude product was boiled with benzene to remove the water. At this stage the crude mixture was dissolved completely in about 1500 parts of boiling benzene and crystallized therefrom. The refined dodecafiuoroheptyl phosphate was further purified by crystalliza- ,tion'irom toluenagivinga product-which.melted at 102 C.-107 C. with slight pink color. :This was purified furtherpby treating an "ethyl 'ether solution ofthegcompound with decolorizing carbon, filtering, evaporating and crystallizing. carefully (from a --benzene-ether, mixture containing avery small amount of ether. .The .fina'l purified mono dodecafluoroheptyl) phosphate.

H(CF2) eCHzOPO (OH) 2 M. P. 111 C.-112'- C., had a neutralequivalent at 203:2 (theoretical 206).

EXAMPLE'IVr-CQ 'ESTERS Mixed phosphate esters of hewadecafluorouonanoL-To parts of .hexadecafiuorononan'ol, H(CF2)8CH2OH (0.116 mol) were addedfiparts (0.04 mol) of phosphorus pentoxide. .Theseflingredients were mixed intimately and heated to 120 C.140 C. To five parts=of the crude ester thus formed were added 2.5 parrsof 28% aqueous ammonium hydroxide, followed by dilutionto 100 parts with water. This gave a mixtureofammonium salts of hexadecafluorononyl phosphates.

D Zia-m m 0 n i u m hemadecafluorononyl -.phosminutes-43.2 parts (0.10 mol) of hexadecafluorononanol were dissolved in 45 parts of toluene and '7 .1 parts (0.05 mol). of phosphorus pentoxide added. The mixture was stirred at 60 C.f70 C.-for 2.5 hours. Two parts of water were added-and the mixture refluxed inv order to hydrolyze the phosphoanhydrides formed. The mixture was dissolved in 500 parts of dioxane and treated twice with decolorizing carbon. Thereupon the mixture was gassed with ammoniato precipitate the diammonium hexadecafiuorononyl phosphate which was dissolved in ethanol, boiled momentarily with benzene to remove water, and the insoluble ammonium filtered off. The diammonium hexadecafluorononyl phosphate was then precipitated by boiling oh the ethanol with benzene. 25 parts of the diammonium salt was obtained. By diluting the dioxane solution with toluene an additional 11.5 parts of the diammonium salt was yielded, making the final yield 69% Analysis: percent P, 5.95, 5.93 percent N, 2.65.

EXAMPLE V.Cll, ESTERS Tri (ez'cosufluoroundecz Z) phosphate-.-This ester was prepared in the manner described above in connection with the diammonium salt in Example IV but using 100 parts (0.183 mol) of eicosafiuoroundecanol, H(CF2)10CH2OH, 16 parts of pyridine, and 9.2 parts (0.06 mol) of phosphorus oxychloride in parts of xylene. The ester formed was washed with water and crystallized from toluene and methanol, successively. This ester was a white powder with a melting range of 115.1' C.115.5 C., and contained 2.09% P (theory 1.89% P).

A m m 0 n i u m di(eicosafluoroundecyl) phosphate-14 parts of phosphorus pentoxide were added to 106 parts of eicosafluoroundecanol at (3., the temperature raised to 200 C. and held there for 45 minutes, and then reduced to room temperature. The reaction mixture was then distilled over a range of 30 C.28.0 C. at 0003-0008 mm. pressure. Titration of the distillate showed only one active hydrogen. It was dissolved in boiling toluene and gaseous ammonia bubbled into the solution, thus precipitating the ammonium salt of di(eicosafiuoroundecyl) phosphate containing 3.46% P and 1.39% N. It changed from a solid to a liquid at 180 C.-

190 C. in a sealed tube and at 182.5 6-199 C.

in an open tube.

Diammonium eicosafluoroundecyl phosphate.- 53.2 parts (0.10 mol) of eicosafluoroundecanol were dissolved in 45 parts of toluene at 70 C. and 7.1 parts (0.05 mol) of phosphorus pentoxide were added. The mixture was kept at 70 0.. with stirring for one hour and refluxed for 30 minutes. Two parts of water were added to hydrolyze the reaction products and the entire mixture was then dissolved in dioxane. The dioxane solution was treated twice with decolorizing carbon and gassed with anhydrous ammonia. 28 parts of diammonium eicosafluoroundecyl phosphate were precipitated. This was dissolved in absolute ethanol and precipitated by boiling oif ethanol with benzene. There was thus obtained a yield of 44.5% of the diammonium salt.

Analysis calculated for N, 4.33. Found: N, 4.39.

It will be understood that the above examples are merely illustrative and that the present invention broadly comprises the class of fiuoroalkylphosphoric compounds having the formula (HQCFz) 21101120) .rPO(OM)y wherein n is an integer from 1 to 5, inclusive, x is an integer from 1 to 3, inclusive, 3 equals 3a7, and M is hydrogen, alkali metal, ammonium or substituted ammonium.

In the manner disclosed hereinbefore and illustrated in the numerous examples, the other compounds of the defined class of this invention may be prepared. These compounds include both the fluoroalkylphosphoric esters and the salts of these esters with ammonia, the alkali metals such as potassium, sodium, and lithium, and amines, particularly the alkylamines of 1 to 6 carbon atoms such as ethylamine, diethylamine,

butylamine, and hexylamine, and the tetraalkyl ammonium bases corresponding to these amines. Because of their special utility as dispersing agents, the ammonium and alkali metal salts are preferred, especially the ammonium salts of the monoand difiuoroalkylphosphoric esters.

The compounds of this invention are useful for a wide variety of purposes. Those having the requisite water solubility, which may be relatively very slight, are useful surface-active a ents.

They are particularly adapted as dispersing agents in the polymerization of haloolefines, where dispersions of the polymers are obtained with difficulty, if at all, from polymerization in aqueous medium in the presence of ordinary dispersing agents. Failures in this respect encountered in the polymerization of haloolefines, especially tetrafluoroethylene, are generally attributed to chain termination caused by conventional dispersing agents. Thus, the subject compounds are admirably suited for aqueous polymerization of tetrafluoroethylene and chlorotrifluoroethylene because of the inertness of their alkyl chains.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

The invention claimed is:

1. A fiuoroalkylphosphoric compound having the formula (H(CF2)21LCH2O)$PO(OM)1I wherein n is an integer from 1 to 5, inclusive, :1: is an integer from 1 to 3, inclusive, 2/ equals 3-20, and M is from the group consisting of hydrogen, alkali metal, ammonium, and substituted ammonium.

2. A fiuoroalkylphosphoric compound having the formula (H (CF2) znCH2O) 30 (ONH4) y wherein n is an integer from 1 to 5, inclusive, :1: is an integer from 1 to 3, inclusive, and y equals 3-2:.

3. A fiuoroalkylphosphoric compound as set forth in claim 2 wherein a: is an integer from 1 to 2, inclusive.

ANTHONY F. BENNING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,411,159 Hanford Nov. 19, 1946 2,451,375 Bell Oct. 12, 1948 OTHER REFERENCES Swarts, Rec. Trav. Chim., vol. 28, pp. 166-170 (1909). 

1. A FLUOROALKYLPHOSPHORIC COMPOUND HAVING THE FORMULA (H(CF2)2NCH2O)XPO(OM)Y WHEREIN N IS AN INTEGER FROM 1 TO 5, INCLUSIVE, X IS AN INTEGER FROM 1 TO 3, INCLUSIVE, Y EQUALS 3-X, AND M IS FROM THE GROUP CONSISTING OF HYDROGEN, ALKALI METAL, AMMONIUM, AND SUBSTITUTED AMMONIUM. 